Cocaine's reinforcing effects are believed to be related to its ability to inhibit dopamine uptake. From behavioral studies, it appears thD the D -(1), D-(2), D-(3), (and perhaps D-(4)) receptor subtypes are involved in the reinforcing effects of cocaine. Selective antagonists for these receptor subtypes might be useful in the treatment of cocaine vs. D-(1) and D-(2) may be especially useful. Computational studies are currently underway to aid in the design of selective D-(3) (and D-(4)) antagonist compounds. We require structural data for as man high-activity D-(2) and DC-(3) compounds as possible to aid in our molecular modeling studies. This requested starting grant will be used to search x-ray crystallographic databases for that information.